A matrix of applications that have been (or are being) built for the laptop can be found here.

OLPC software is a set of carefully chosen and integrated Linux applications, creating an innovative user environment.

Basically, the laptop runs Red Hat's Fedora Linux Core 7; On top of the X Window System and the Matchbox window manager, we run a novel Sugar user interface and support library, supporting a core set of "activities". Activities are programs that follow the OLPC Human Interface Guidelines. There is an emphasis on Python and GTK. Other Linux software can be run too, but having a common and enabling user interface is nice; requiring additional libraries (KDE, java runtime, whatever) is in tension with disk and memory limits.